1. Technical Field
The present invention relates generally to a bone grinding apparatus having a portable design for cutting bone into bone tissue particles for application in medical procedures.
2. Background Art
Numerous medical procedures require the donation of human organs and tissues. Bone is one of the required human tissues needed for many of these medical procedures. Among other uses, donated bone samples are used as adhesives and grafting material in bone grafting operations, as protective layers in prosthetic implants, and as bone tissue composites in the creation of screws, disks, plates, pins, and joint sockets used in corrective surgeries. Regardless of the ultimate form in which donated bone is used, donated bone samples must first be processed by a grinding apparatus into bone tissue powder. The bone tissue powder is then demineralized and used in the previously mentioned capacities to facilitate the medical operation.
Several attempts have been made to create devices that correctly mill the bone samples into a useable powder form. Numerous issues have arisen that have complicated this process. First of all, many conventional bone grinding systems require a two stage milling operation using separate pieces of equipment. These prior art devices lack the ability to transform the donated sample directly into bone tissue powder. This requires the bone to be ground first into intermediary pieces within one grinding apparatus, and then the pieces must be physically transferred to a second apparatus that then converts the pieces into the bone tissue powder form required in medical procedures. Since these prior art devices require multiple pieces of equipment, which necessitates a transfer of the bone specimen between the pieces of equipment, these prior art devices fail to adequately and efficiently transform human bone into the needed bone tissue powder and contamination can occur.
A second drawback of conventional bone grinding systems is the likelihood of contamination of the bone sample during the grinding process. Throughout the grinding process, the bone sample must remain in a sterile environment. Conventional bone grinding devices fail to adequately protect that sterile environment due to the drive portion of these devices being physically located in the same area as the dispensing portion. For example, Grooms U.S. Pat. No. 5,918,821 has the motor portion of the grinding apparatus in close proximity to the dispensing portion. Thus, numerous samples of bone tissue run a high risk of contamination during the operation of the Grooms' apparatus. Also, any maintenance or repair work on any portion of the Grooms' grinding apparatus requires the entire apparatus be removed from the surgical environment in order to maintain a sterile medical facility. Therefore, the Groom's patent fails to adequately prevent the contamination of bone tissue, which is detrimental to the sterility requirement of bone tissue powder in medical applications.
Attempts to alleviate this contamination issue have been unsuccessful in the past. For example, Dowd U.S. Pat. No. 5,607,269 discloses a bone grinding apparatus that has its drive system enclosed in a box. This box initially separates the drive portion of the grinding apparatus from the location where the bone is processed. However, once the bone has been processed, the Dowd invention still requires the bone to be brought through the same environment that contains the drive mechanism before the ground bone is used for its medical purpose. Therefore, the Dowd patent fails to address the contamination issues associated with the processed bone and the drive mechanism for the grinding apparatus sharing the same surgical environment.
Another problem associated with grinding bone into usable bone tissue powder is the breakdown of morphogenetic proteins, which leads to a reduction in osteoinductivity. Osteoinductivity is a characteristic of bone tissue powder necessary to make the bone tissue powder useful within the human body. Morphogenetic proteins are the main element within the bone that maintains osteoinductivity. The major enemy to the morphogenetic proteins is the heat produced during the grinding process. The heat produced in most grinding devices is unchecked due to the lack of a controlled automated process that regulates the speed of the cutting elements and the pressure and rate at which the bone sample is fed to the cutting elements.
For example, the Grooms patent requires a human user to manually press on a plunger in order to supply the bone to its grinding elements. This manual process fails to maintain a consistent pressure or speed with which the bone sample is supplied to these grinding elements.
The Dowd apparatus also fails to maintain a consistent pressure or speed of the bone sample during the grinding process. The Dowd patent uses a holding vice to support the bone sample as a drill bit shaves off bone particles. The processing portion of the Dowd apparatus is not pressurized and lacks the controlled environment necessary in creating a consistent pressure and speed of the bone sample supplied to the grinding element. Thus, the Dowd device also fails to efficiently maintain the osteoinductive characteristic of the bone sample used in the grinding process.
Additionally, in U.S. Pat. No. 6,755,365 issued to the inventor of the present invention, a bone grinder is disclosed which is automated and which can sterilely process bone into bone tissue power for use in medical procedures, the disclosure of which is herein incorporated by reference in its entirety. The invention of the U.S. Pat. No. 6,755,365 essentially comprises a grinding chamber, primary and secondary cutting elements positioned within the grinding chamber to sequentially perform primary and secondary cutting operations on the bone, and a drive mechanism engaging primary and secondary cutting elements. While the invention of U.S. Pat. No. 6,755,365 is very able and efficient at grinding bone, there is also a need for a different type of bone grinder which may provide an easier and more efficient application for surgical procedures.
Unfortunately, many bone grinders of the prior art are additionally burdened with complicated cleaning procedures which may include sterilization through an autoclave system in order to preclude contamination of a patient by a previous patient and bone sample. In addition, many prior art bone grinders are cumbersome, lack an easy to clean design and furthermore do not adequately capture ground bone for use in medical procedures.
What is desired therefore is a bone grinder which is easier to clean while also being ideal for operating room type procedures. Indeed, a combination of characteristics including an efficient and user friendly design not realized in the prior art as well as an improvement over prior art bone grinders have been found to be necessary for bone grinders used in a variety of medical settings. Also desired is a bone grinder that is easy to move and further that does not require autoclave sterilization techniques between uses.